This invention relates to a generally cylindrical spring provided with windows through which wedging cams extend. The spring is adapted to act on said wedging cams when they are engaged between the internal and external races of a free-wheeling device utilizing wedging cams. Said wedging cams may advantageously be held in windows formed in a cage. A certain number of embodiments of such springs are known. In these devices the springs bear on lateral surfaces of the cams of the free-wheeling device. These known springs have windows the edges of which define tongues which bear on the lateral faces of the wedging cams. (See for example U.S. Pat. Nos. 2,753,027; 3,219,163 and German Pat. No. 1,142,254.)
With these devices of a known type, certain difficulties are encountered in practice because the synchronization of the assembly of cams is poor. It has been found, in fact, that there is frequently a certain lack of rapidity in the response of the cams when the device is urged in the locking direction which appears to be due to an imperfect synchronization of the assembly of cams.
This defect appears to be due to the fact that springs of the known type generally act on the wedging cams only at two pivot points, with the swinging of one of the cams causing practically no reaction on the other adjacent cams.
An attempt has already been made to overcome this type of disadvantage by providing, for example, two concentric cages in a free-wheeling device, the spring being mounted between the cages which come in contact with the wedging cam and synchronize their movements (French Pat. No. 1,095,050). It will, however, be understood that such a device has the disadvantage of multiplying the number of elements and thus increasing the complexity and cost of the free-wheeling device.
It is the object of the present invention to provide a spring for a free-wheeling device of the type utilizing wedging cams which is simple to make and which, by reason of its configuration, holds the cams perfectly in position and provides a floating mounting for said cams so as to obtain an improved synchronization and less wear on the cams. The spring according to the invention makes it possible to limit the drag torque of the free-wheeling device while making it possible to define the position of the cam with greater precision during free-wheeling operation.
It is also an object of the invention to provide a spring the configuration of which is such that centrifugal force caused by rotation of the free-wheeling device has a tendency to provoke at high speeds of rotation, a pivotal movement of the cams which reduces their wear.
It is a further object of the invention to provide an assembly formed by a plurality of cams, a spring acting on the cams, and a cage so that this assembly forms a perfectly cohesive unit.
Another object of the invention is to provide a device of the free-wheeling type using wedging cams which is equipped with a spring adapted to limit the wear of the cams and the races while assuring improved synchronization of the assembly of cams during wedging.
The springs of the free-wheeling device utilizing wedging cams according to the invention comprises windows through which the cams pass and at least one tongue coming to bear on each cam. In accordance with the invention the spring has a series of principal undulations provided with windows and separated from each other by substantially cylindrical portions. Each principal undulation has, near its summit, a secondary undulation which thus exists on each side of the windows. The dimensions of these windows are such that their edges grip the cams on entry in substantially perpendicular contact with the lateral faces of the cams. A swinging tongue is moreover formed in the spring and bent toward the outside so as to act on one of the lateral faces of each cam in the direction which improves the wedging action. The swinging tongue preferably has a flat portion capable of entering into contact with one corresponding flat portion of the lateral face of the cam in sliding position in order to precisely define this position.
In a preferred embodiment the tongue has a trapezoidal profile the width of which decreases toward the free end so as to impart thereto a substantially equal resistance to the flexing over its entire length. Moreover, the edges of the tongue are connected to the spring in a substantially cylindrical portion of the latter and tangentially to perforations formed in the spring on each side of the tongue in order to avoid the initiation of cracks. In another embodiment of the invention the wedging contact between the cam and the edge of each window opposite the swinging tongue is produced by means of one or more wedging tongues curved toward the inside and having a rounded zone of contact. It is thus possible to decrease the strains on the secondary undulation of the spring .